[libvirt] [PATCH V3 3/3] libxl: drop virDomainObj lock when destroying a domain

[Jim Fehlig]

A destroy operation can take considerable time on large memory
domains due to scrubbing the domain's memory.  Unlock the
virDomainObj while libxl_domain_destroy is executing.

Implement libxlDomainDestroyInternal wrapper to handle unlocking,
calling destroy, and locking.  Change all callers of
libxl_domain_destroy to use the wrapper.

Signed-off-by: Jim Fehlig <jfehlig at suse.com>
---

V3:
Provide a wrapper to unlock, destroy and lock domain instead of
do so at each call site of libxl_domain_destroy.

 src/libxl/libxl_domain.c    | 29 ++++++++++++++++++++++++++---
 src/libxl/libxl_domain.h    |  4 ++++
 src/libxl/libxl_driver.c    |  6 +++---
 src/libxl/libxl_migration.c |  4 ++--
 4 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c
index 37ed082..1b809ca 100644
--- a/src/libxl/libxl_domain.c
+++ b/src/libxl/libxl_domain.c
@@ -435,7 +435,7 @@ libxlDomainShutdownThread(void *opaque)
         libxlDomainEventQueue(driver, dom_event);
         dom_event = NULL;
     }
-    libxl_domain_destroy(cfg->ctx, vm->def->id, NULL);
+    libxlDomainDestroyInternal(driver, vm);
     libxlDomainCleanup(driver, vm, reason);
     if (!vm->persistent)
         virDomainObjListRemove(driver->domains, vm);
@@ -447,7 +447,7 @@ libxlDomainShutdownThread(void *opaque)
         libxlDomainEventQueue(driver, dom_event);
         dom_event = NULL;
     }
-    libxl_domain_destroy(cfg->ctx, vm->def->id, NULL);
+    libxlDomainDestroyInternal(driver, vm);
     libxlDomainCleanup(driver, vm, VIR_DOMAIN_SHUTOFF_SHUTDOWN);
     if (libxlDomainStart(driver, vm, false, -1) < 0) {
         virErrorPtr err = virGetLastError();
@@ -626,6 +626,29 @@ libxlDomainSaveImageOpen(libxlDriverPrivatePtr driver,
 }
 
 /*
+ * Internal domain destroy function.
+ *
+ * virDomainObjPtr must be locked on invocation
+ */
+int
+libxlDomainDestroyInternal(libxlDriverPrivatePtr driver,
+                           virDomainObjPtr vm)
+{
+    libxlDriverConfigPtr cfg = libxlDriverConfigGet(driver);
+    int ret = -1;
+
+    /* Unlock virDomainObj during destroy, which can take considerable
+     * time on large memory domains.
+     */
+    virObjectUnlock(vm);
+    ret = libxl_domain_destroy(cfg->ctx, vm->def->id, NULL);
+    virObjectLock(vm);
+
+    virObjectUnref(cfg);
+    return ret;
+}
+
+/*
  * Cleanup function for domain that has reached shutoff state.
  *
  * virDomainObjPtr must be locked on invocation
@@ -1022,7 +1045,7 @@ libxlDomainStart(libxlDriverPrivatePtr driver, virDomainObjPtr vm,
         libxl_evdisable_domain_death(cfg->ctx, priv->deathW);
         priv->deathW = NULL;
     }
-    libxl_domain_destroy(cfg->ctx, domid, NULL);
+    libxlDomainDestroyInternal(driver, vm);
     vm->def->id = -1;
     virDomainObjSetState(vm, VIR_DOMAIN_SHUTOFF, VIR_DOMAIN_SHUTOFF_FAILED);
 
diff --git a/src/libxl/libxl_domain.h b/src/libxl/libxl_domain.h
index 30855a2..aa647b8 100644
--- a/src/libxl/libxl_domain.h
+++ b/src/libxl/libxl_domain.h
@@ -103,6 +103,10 @@ libxlDomainSaveImageOpen(libxlDriverPrivatePtr driver,
                          libxlSavefileHeaderPtr ret_hdr)
     ATTRIBUTE_NONNULL(4) ATTRIBUTE_NONNULL(5);
 
+int
+libxlDomainDestroyInternal(libxlDriverPrivatePtr driver,
+                           virDomainObjPtr vm);
+
 void
 libxlDomainCleanup(libxlDriverPrivatePtr driver,
                    virDomainObjPtr vm,
diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
index c9623ef..9eb071e 100644
--- a/src/libxl/libxl_driver.c
+++ b/src/libxl/libxl_driver.c
@@ -1252,7 +1252,7 @@ libxlDomainDestroyFlags(virDomainPtr dom,
     event = virDomainEventLifecycleNewFromObj(vm, VIR_DOMAIN_EVENT_STOPPED,
                                      VIR_DOMAIN_EVENT_STOPPED_DESTROYED);
 
-    if (libxl_domain_destroy(cfg->ctx, vm->def->id, NULL) < 0) {
+    if (libxlDomainDestroyInternal(driver, vm) < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        _("Failed to destroy domain '%d'"), vm->def->id);
         goto endjob;
@@ -1595,7 +1595,7 @@ libxlDoDomainSave(libxlDriverPrivatePtr driver, virDomainObjPtr vm,
     event = virDomainEventLifecycleNewFromObj(vm, VIR_DOMAIN_EVENT_STOPPED,
                                          VIR_DOMAIN_EVENT_STOPPED_SAVED);
 
-    if (libxl_domain_destroy(cfg->ctx, vm->def->id, NULL) < 0) {
+    if (libxlDomainDestroyInternal(driver, vm) < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        _("Failed to destroy domain '%d'"), vm->def->id);
         goto cleanup;
@@ -1802,7 +1802,7 @@ libxlDomainCoreDump(virDomainPtr dom, const char *to, unsigned int flags)
     }
 
     if (flags & VIR_DUMP_CRASH) {
-        if (libxl_domain_destroy(cfg->ctx, vm->def->id, NULL) < 0) {
+        if (libxlDomainDestroyInternal(driver, vm) < 0) {
             virReportError(VIR_ERR_INTERNAL_ERROR,
                            _("Failed to destroy domain '%d'"), vm->def->id);
             goto unpause;
diff --git a/src/libxl/libxl_migration.c b/src/libxl/libxl_migration.c
index 3d0c96e..4010506 100644
--- a/src/libxl/libxl_migration.c
+++ b/src/libxl/libxl_migration.c
@@ -575,7 +575,7 @@ libxlDomainMigrationFinish(virConnectPtr dconn,
 
  cleanup:
     if (dom == NULL) {
-        libxl_domain_destroy(cfg->ctx, vm->def->id, NULL);
+        libxlDomainDestroyInternal(driver, vm);
         libxlDomainCleanup(driver, vm, VIR_DOMAIN_SHUTOFF_FAILED);
         event = virDomainEventLifecycleNewFromObj(vm, VIR_DOMAIN_EVENT_STOPPED,
                                          VIR_DOMAIN_EVENT_STOPPED_FAILED);
@@ -614,7 +614,7 @@ libxlDomainMigrationConfirm(libxlDriverPrivatePtr driver,
         goto cleanup;
     }
 
-    libxl_domain_destroy(cfg->ctx, vm->def->id, NULL);
+    libxlDomainDestroyInternal(driver, vm);
     libxlDomainCleanup(driver, vm, VIR_DOMAIN_SHUTOFF_MIGRATED);
     event = virDomainEventLifecycleNewFromObj(vm, VIR_DOMAIN_EVENT_STOPPED,
                                               VIR_DOMAIN_EVENT_STOPPED_MIGRATED);
-- 
1.8.4.5